Would increasing the supply of doctors lead to lower health costs? This question came up repeatedly in my reporting for Monday's article about barriers to entry for foreign-trained physicians. It seems as if there should be a pretty straightforward answer, based on the usual laws of supply and demand: If you artificially limit the supply of doctors, that should push up the prices of the services they provide. So if you suddenly increase the supply of doctors, that should lower health care costs. But economists are divided about the role that the supply of doctors plays in health spending because health care is a funny market, given information asymmetries and third-party payers.